does anybody know how to adjust the infinity point in th econtax 645 lenses and if possible to do it myself? my lenses have slightly different inf. points.

Like all autofocus lenses, they all probably focus past infinity. This assures that you will attain infinity focus under all circumstances and conditions with the lens. If you not reaching infinity with one or more of the lens, the lenses will have to be sent to Contax (or their designated service center) for adjustment. It is not something you can do yourself.